This invention relates, in general, to semiconductor processing, and, more particularly, to X-ray lithography.
Recently, there has been increased interest in X-ray lithography as demands for continually smaller features increase. Additionally, this interest has been further extenuated as it becomes increasingly hard to provide these small images or features with optical photolithography. Use of X-ray lithography potentially has several advantages, such as being able to image smaller features, higher lithographic performance, and is potentially more manufacturable.
While these advantages are theoretically possible, conventional baking processes used in the manufacture of X-ray masks do not allow these advantages to be realized across an imaging field of the X-ray mask.
Conventionally, during the manufacture of X-ray masks, baking processes generally are achieved by either a convection baking process or a hot plate baking process. In the convection baking process, a convection oven is used. The X-ray mask is placed in the convection oven and baked for a prescribed period of time. However, convection ovens are not capable of precise temperature control due to a variety of factors, such as a large volume, movement of convection currents of air in the oven, poor control systems, or the like, thus making the convection oven process not suitable for baking of X-ray mask. In the hot plate baking process, a hot plate is used. The X-ray mask is placed on the hot plate and baked for a prescribed period of time. However, while the hot plate baking process is better than the convection oven baking process, the conventional hot plate baking process is not sufficient for precise baking of X-ray masks. Thus, neither the hot plate baking process nor the convection process allows for precision baking of X-ray masks so as to be able to image fine lines and spaces of equal uniformity across the entire chip field of an X-ray mask.
It can be seen that use of conventional baking processes does not meet the requirements for today's manufacturing of X-ray masks. Therefore a baking process that is precise enough to allow imaging of extremely small lines and spaces of equal uniformity across the entire chip field would be highly desirable.